1.0 Field of the Invention
This invention relates to application server provisioning; and in particular, this invention relates to application server provisioning by disk image inheritance.
2.0 Description of the Related Art
In the current service-oriented Information Technology (IT) business market, fast and on-demand application server provisioning is a significant requirement for a data center. An “application server” is a computer that executes at least one software application in order to serve at least one client computer. A typical data center may host one or more customers; and each customer is typically provided with at least one application server. The software that is executed by an application server is referred to as application server software. The application server may have its own local disk, or may use a disk in a storage area network. The disk contains the software that is to be executed by the application server.
Various tools are used to create a full disk image to backup a disk in a computer system, and this backup image can be used to restore the disk in the event of a failure. To provision software for a new application server using one well-known method, a service provider copies a single full backup image of a disk that contains all the desired software applications to a disk from which the software will be executed by the application server. Using this method, an application server can typically be provisioned in a few minutes.
Application server software can have many options. Different customers typically use different application servers having, for example, different types of server machines and different software applications including operating systems. Using one technique, in order to provision application server software in a timely manner, the provisioning service provider prepares and maintains full disk images comprising many, or all, the application server software options. This results in a large number of full disk images which need to be stored. Each full disk image of the application server software contains all the software applications, typically including the operating system, of that application server software. Storing those full disk images consumes a large amount of storage. For example, assume that a data center has four different server machine types, three different operating systems, two versions of a database server, such as, the IBM® (Registered trademark of International Business Machines Corporation) DB2® (Registered trademark of International Business Machines Corporation) server, and two versions of an IBM WebSphere® (Registered trademark of International Business Machines Corporation) Application Server (WAS 6 and WAS 5). In addition, the DB2 server and WAS can be installed in same application server or in separate application servers. Therefore, in this example, there are a total of ninety-six (4×3×(2+2+2×2)=96) different possible options of application server software. To provide all possible different options, the service provider stores ninety-six full disk images of the application server software. Considering that the typical disk size of an application server is very large, for example, twenty gigabytes (20 G), storing ninety-six different full disk images of twenty gigabyte disks will consume 1.92 terabytes (96×20 G=1920 G) of storage space. In practice, a data center may have even more installation options and therefore an even larger storage requirement, which makes disk image-based application server software provisioning difficult to implement.
Therefore, there is a need for an improved technique for provisioning application server software.